1. Technical Field
This disclosure relates to wireless mobile device locating systems and to portable call collection units that test the accuracy of such locating systems.
2. Description of Related Art
FCC regulations require wireless mobile communication device carriers to quickly and automatically determine the location of cellphones when they place enhanced 911 calls and to provide this location information to public safety answering points (PSAPS).
Carriers have built and installed wireless mobile device locating systems that determine and provide this location information. The accuracy of these systems must be tested, and the results of these tests must be provided to the FCC.
To perform these tests, call collection units are installed in test vehicles and the test vehicles are driven within a service area. However, a service area may be so large as to make it impractical for the entire area to be tested with just a few test vehicles, particularly when re-testing is needed due to system repairs and upgrades.
To help with this problem, call collection units can be made portable so that they can be moved from one vehicle to another. However, making the units portable can give rise to another problem: When power to the portable unit is removed, synchronization between an internal time clock in the call collection unit and time signals that are periodically transmitted as part of the GPS signals can be lost. This can cause the tests results to be inaccurate.